In current solar cell technology, a photoelectric conversion active layer or an absorber is used for converting light energy, from the sun for example, into electrical energy. A solar cell has an upper electrode layer and a lower electrode layer on the upper surface and the lower surface of the absorber, respectively. When receiving light, the absorber separates electric charges to the upper electrode layer and the lower electrode layer, thereby generating voltages and currents. The photo-generated voltages and currents can vary due to different material properties of the absorbers, as well as different light receiving areas and illuminating intensity of the solar cells. Under the same illuminating intensity, the photocurrent increases as the light receiving area rises. The output voltages, however, cannot be increased by increasing the light receiving area. The electrical power tends to be wasted under the circumstance of lower voltage with high current. Hence, isolated solar cells are interconnected in series to raise the output voltage of a solar cell module, thereby avoiding the waste of electrical power. In addition, these isolated solar cells can be connected in parallel for raising the current if needed.
Typically, solar cells are cut into rectangular shapes. For the serial interconnection of the first solar cell and the second solar cell, manufactures may arrange them next to each other (namely, side by side) with their upper electrode layer facing up, and using a conductive material to electrically connect the upper electrode layer of the first solar cell with the lower electrode layer of the second solar cell. The manufactures usually make the conductive material electrically connect to the upper electrode layer of the first solar cell, and then make the conductive material run through the gap between the first solar cell and the second solar cell. Subsequently, the manufactures flip the first solar cell and the second solar cell to make their lower electrode layers face up, and making the conductive material in the gap electrically connect to the lower electrode layer of the second solar cell. However, there should be enough space for the solar cells to flip upside down, especially when there are many of them interconnected in series.
Consequently, a method for interconnecting solar cells without flipping them was developed. In this method, manufactures made the upper electrode layer of the first solar cell and the lower electrode layer of the second solar cell face up before electrically connecting them with a conductive material with enough width for making the interconnection. Although this approach does not need to flip over the solar cells, it wastes a large amount of conductive materials. In addition, a larger area of the solar cell is blocked by the conductive material so that the conversion efficiency is worsened. Moreover, the alignment of the conductive material has to match the positions of the first and the second solar cells precisely to avoid poor electrical interconnection. This makes the manufacturing of the solar cell module difficult.